PARTIAL TORUS INSTABILITY
PARTIAL TORUS INSTABILITY
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DOI：
10.1088/0004-637x/718/1/433
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发表时间：
2010-07
期刊：
影响因子：
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通讯作者：
O. Olmedo;Jie Zhang
中科院分区：
文献类型：
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作者：
O. Olmedo;Jie Zhang
通量绳现在被普遍认为是日冕物质抛射（cme）的磁性结构，它可能在太阳爆发之前或期间形成。在本研究中，我们将通量绳建模为载流部分环面环，其两个足点锚定在光球中，并在环面不稳定性（TI）的背景下研究其稳定性。以往对TI的研究主要集中在环面的结构上，并揭示了上覆约束磁场的临界衰减指数的存在。我们的研究表明，临界指数是部分环面分数的函数，由光球上方部分环面的弧长与等半径环面的周长之比来定义。我们将这一发现称为部分环面不稳定性（PTI）。发现分数越小的部分环面具有越小的临界指数，因此需要一个逐渐减小的磁场来稳定磁链。另一方面，分数较大的部分环面具有较大的临界指数。在环面的极限中，当分数接近1时，临界指数达到最大值。我们证明PTI可以帮助我们理解通量绳CME的限制、生长和最终喷发。
Flux ropes are now generally accepted to be the magnetic configuration of coronal mass ejections (CMEs), which may be formed prior to or during solar eruptions. In this study, we model the flux rope as a current-carrying partial torus loop with its two footpoints anchored in the photosphere, and investigate its stability in the context of the torus instability (TI). Previous studies on TI have focused on the configuration of a circular torus and revealed the existence of a critical decay index of the overlying constraining magnetic field. Our study reveals that the critical index is a function of the fractional number of the partial torus, defined by the ratio between the arc length of the partial torus above the photosphere and the circumference of a circular torus of equal radius. We refer to this finding as the partial torus instability (PTI). It is found that a partial torus with a smaller fractional number has a smaller critical index, thus requiring a more gradually decreasing magnetic field to stabilize the flux rope. On the other hand, a partial torus with a larger fractional number has a larger critical index. In the limit of a circular torus when the fractional number approaches 1, the critical index goes to a maximum value. We demonstrate that the PTI helps us to understand the confinement, growth, and eventual eruption of a flux-rope CME.